Cummins ISL CM850 (2003-06) Fault Code: 428 (Auto) PID: 97 SPN: 97 FMI: 3 Water-in-Fuel Indicator Sensor Circuit – Voltage Above Normal or Shorted to High Source. High voltage detected at the water-in-fuel circuit.

The water-in-fuel sensor is integrated into the fuel filter. It is automatically replaced whenever the fuel filter is replaced. For marine applications, the sensor is not integrated into the fuel filter and is a serviceable item.

Possible causes:

1)Open RETURN or SIGNAL circuit in the harness, connectors, or sensor.
2)SIGNAL wire shorted to sensor supply or battery voltage.

Possible repairs:

1)Replace the water-in-fuel sensor.
2)Repair or replace the damaged engine harness.
3)Replace the ECM.